Modified double solvent treatment



Patented Jan. 15, 1 952 UNITED STATES PATENT OFFICE f ass'bisfia'MODIFIED DOUBLE SOLVENT]? TREATMENT Harold C. Myers, Woodbury,assignorto Socony-Vacuum Oil Company, Incorporated, a corporation of NewYork No Drawing. Application August 27,1947,

. Serial No. 770,951

The present invention relates to the separation of mixtures ofhydrocarbons into aparaffinic portion and a non-Vparaffinic portion and,more particularly, to the refining of petroleum oil and the like to araifinate of higher parafinicity than the charge stock.

- The so-called double solvent processes of solvent treating petroleumoil employs 'two solvents of relatively low mutual solubilities, one ofwhich has a high preferential solubility for the undesirableconstituents of the oil, usually classified as non-paraffinic ornaphthenic and aromatic hydrocarbons, and the other a high preferentialsolubility for the desirable constituents of the oil, usually classifiedas parafiinic hydrocarbons. The first solvent is usually referred to asthe naphthenic' solvent while the other solvent is usually referred toas the paraffinic solvent. The raffinate phase in the double-solventtreatment is a solution of the more paraffinic portion of the charge oilin the paraflinic solvent'while the'extract phase is a solution ofundesirable constituents or non-paraffinic constituents in thenaphth'enic solvent.

A brief but adequate description of one modi- 1'.

fication of the double solvent method of treating petroleum oil is givenin the Process Handbook section of Petroleum Refiner (April 1947) pagesl3'8and 139. The double solvent process is also described in U. S.Patents Nos. 1,912,348: 1,912,349 and, 2,041,308.

The double solvent refining process which is most widely used in thepetroleum industry for refining residual oils is known as the Duo-Solprocess. The process is capable of simultaneously deasphalting andsolvent refining asphaltic residua by employing a. two-solvent systemcomposed of a naphthenic solvent, selecto, and a parafiinic solvent,liquid propane. Selecto is a mixture of phenol and cre'sylic acidsusually containing 40 to 60 per cent phenol. In a Duo- Sol system, theliquid propane acts as an asphalt precipitant and diluent while selectofunctions both as a solvent for the asphalt and an oil treating agent. Atypical installation consists essentially of a three to seven stagecountercurrent extraction system in which a propane-oil mixture' iscontacted with sel'ecto plus a two stage system in which the selecto,containing ex extracted material. is countercurrently washed 2 withfresh liquid propane. In a seven stage propane would be added to thefirst, charge stock in the third, and selectof inthe seventh stage;

, The spent solvent containing extracted material and asphalt wouldbed-rawn from the first and of synthesis, likewise are amenable to thistreat-;

ment, 7

lI-t hasnow been discovered that the useot amodifier in conjunction withthe parafii-nic and, naphthenic solventsin atypical double solventtreatingprocess results in an increased recovery of the refined oil fromthe non-paraffinic materials .in the charge stock. The refined oilsoobtained is of a quality comparable to that produced intheconventional double solvent treating. process although of somewhathigher viscosity. The rejected: material, i e. the solute of the extractphase, or tar is of higher gravity,

than tar from normal or conventional double solvent operations.

In general, the paraffinic solvents employed in I the; doublesolventtreatment of mixtures ofparaf finic, naphthenic andaromatichydrocarbons with or withoutadmixedasphaltic materials are lique-' fiednormally gaseous hydrocarbons such as the saturated and unsaturatedhydrocarbons havingi 3 to 5 carbon atoms, lighter hydrocarbonszsuch asmethane, ethane, ethylene, acetylene, etc. mixed with hydrocarbons of 3to 5 carbon atoms and-heavier aliphatic and olefinic hydrocarbons havingup to 10 or 12' carbonatoms per molecule.-

Other para-ifii-lic solvents are methyl Cellosolve, Carbitol and-otheroxygenated compounds such asac'etone, methyl, ethyl and isopropyl alco'=hols, etc: v

The naphthenic solvents employed in the" double solvent treatment ofmixtures of past-'- finic, naphthenic and aromatic hydrocarbons with orwithout admixed asphaltic materials are aqueous or non-aqueous liquidS02, liquid SO2- benzol, furfural, dichloroethyl ether, aniline,quinoline, pyridine, nitrobenzene, benzyl alcohol, phenol, cresylicacid, ethylene diamine, diand triethanolamines, crotonaldehyde,sulfolanes, dimethyl formamide, formic acid and acetic anhydride, etc.

When the effects of the foregoing combinations of parafilnic solvent andnaphthenic solvent are modified by the use of a third component,hereinafter termed a modifier, the oily constituents of high viscositypresent in the charge stock are retained in the raflinate phase insteadof being rejected in extract phase as in conventional double solventtreatment. As a result the process yield is higher and the raifinate isof higher viscosity. By modification of other variables a much higheryield of oil of-comparable quality is obtained using the modifiedsolvent combinations than is obtained withconventional solventcombinations.

The solvent combinations are advantageously modified by the use of a.modifier selected from the group consisting of carbonates of aliphatic,cycloaliphatic, and aromatic hydrocarbons and heterocyclic compounds, ofwhich group diethyl carbonate is preferred.

-While the use of one of the afore-enumerated modifiers in conjunctionwith one of the conventional combinations of paraffinic solvent andnaphthenic solvent brings about the advantages enumerated hereinbefore,a more selective action in the presence of smaller amounts of modifiercan be obtained by incorporating small amounts of water, say up to 25weight per cent in the naphthenic solvent.

The modified double solvent refining operation with or without aqueousnaphthenic solvent is conducted in about the same manner as conventionaldouble solvent refining operations withprovision for adding modifier ormodifier andwater at any point or points in the unit. However, improvedresults are obtained by washing the extract phase with fresh parafiinicsolvent-modifier mixture. Thus, for example, in a nine stage systemparaifinic solvent and modifier are added in the first stage, charge oilin the third stage, and aqueous or non-aqueous naphthenic solvent in theninth stage while the treated mixture of hydrocarbons, i. e. mixture ofhydrocarbons of increased parafiinicity, is withdrawn from the ninth andthe rejected extract from the first stage of the unit. The rafiinate andextract are separately treated in any suitable manner, say bydistillation, to remove the paraflinic solvent and the naphthenicsolvent respectively. The ratio of paraflim'c solvent and naphthenicsolvent to charge stock may be varied from 1:1 to 7:1, while themodifier ratio (based on the charge stock) may vary from 0.15 to 15:1.The temperatures employed may vary from '75 to 206 degrees Fahrenheit.

. Those skilled in the art will understand that although the use ofmodifiers in conjunction with the solvents in a double solvent treatmentof a mixture of parafiinic and non-parafilnic hydrocarbons has beendiscussed hereinbefore and will be described hereinafter in conjunctionwith treatment in isolated zones known as stages, nevertheless thetreatment can be carried out in a tower or towers or in equipmentemploying centrifugal force to accelerate the separation of theraflinate phase from theextract phase. Furthermore, the solventtreatment of charge stock with a naphthenic solvent and particularlywith aqueous naphthenic solvents in the absence of a parafiinic solventis improved by the use of the novel modifiers enumerated hereinbefore.

Thus, for example, a mixture of parafiinic and non-paraffinichydrocarbons can be treated in the manner described in the ProcessHandbook section of Petroleum Refiner (April 1947) pages 122 and 123,using dichloroethyl ether, phenol or, in general, any naphthenic solventcontaining up to 10 per cent of water (aqueous naphthenic solvent)together with one or more of the modifiers enumerated hereinbefore.

Typical of the treatment of charge stocks containing parafiinic andnon-parafiinic hydrocarbons are the following non-limiting examples.

EXAMPLE 1 EXAMPLE II In order to provide a standard whereby the effectof the modifiers can be evaluated, a portion of the same stock wastreated at the same temperature with about 300 weight per cent ofnaphthenic solvent of 50 percent phenol content (selecto) and about 500weight per cent of propane.

EXAMPLE III In order to show the efiect produced by using a naphthenicsolvent containing water in conjunction with a parafiinic solvent and amodifier, diethyl carbonate, a charge stock of 458 seconds SayboltUniversal viscosity at 210 degrees Fahrenheit was processed in the sameequipment employing about 350 weight per cent "naphthenic solvent of 50per cent phenol content (selecto) containing about 1.5 per cent ofwater, about 450 weight per cent of propane and about 25 weight per centof diethyl modifier at a temperature of about degrees Fahrenheit.

EXAMPLE IV To provide a standard of comparison for the results obtainedin Example III, a portion of the same charge stock was treated with thesame amounts of the same naphthenic and paraffinic solvents in theabsence of a modifier.

EXAMPLE V tent and about 450 weight per cent of propane at a temperatureof about 120 degrees Fahrenheit.

A summary of the results obtained in each of the Examples I to V isprovided in the following table;

COMPARATIVE Duo-sot REFINiNG DATA ON RESIDUAL STOCKS EMPLOYI'NG AS THESELEOIO, SELECTO-WATER WITH LIQUID PROPANE DIE'IHYL CARBONATE DiethylCarbonate Ratio Based on Oil Phenol Content of Selecto, Per Cent WtWater Content of Selecto, Per Cent Wt Run Number Percolation, Oil/ClayRatio by Wt 0. 8:1 1. 4:1 Yields, Per Cent Vol;

11 Process Extraction 84. 1 78. 9 Dewaxing, Ultimate 75. 8 75. 2

Overall- On Residuum 58. 9 54. 8 On Crude 23.4 13. 8 12.8

Raw Waxy Dewaxed Finished Waxy Dewaxed Finished Resid Rafi. Rafi. OilRafi. Rafi. Oil

Processing Step:

Inspections- Crravity, A. P. I Gravity, Specific 60 F. (Pyc 77 F.) PourPoint, F Flash Point, F. (GOO). Fire Point, F. (COC) K. V. 100 F.(Centistokes).

210 F. (Centistokes) S. U. V. 100 F., Seconds 210 F., Seconds. ViscosityIndex Viscosity Gravity Constant 210 F- Color, Lovibond, 34 Cell CarbonResidue, Per Cent Wt. Sulfur, Per Cent Wt '0 o @F (P @77F) peci c r. ycS. U. V. 210 F., Seconds Processing Conditions:

Duo.ol Refining Oil-Selecto-Propane Ratio by Wt Temperature, T

Diethyl Carbonate Ratio Based on Oilfle Phenol Content oiSelecto. PerCent Wt" Water Content of Selecto, Per Cent Wt Run Number Percolation,Oil/Clay Ratio by Wt Yields, Per Cent Vol.:

On Process- Extraction Dewaxing, Ultimate Overall On Residuum On CrudeWaxy Raff.

Finished Oil Finished Oil Processing Step:

lnspections Gravity, A. P. I Gravity. Specific 60 F. (Pyc 77 F.). PourPoint, F Flash. Point. F. (COG) Fire Point, F. (00C) K. V. 100 F.(Centistokes) 210 F. (Centistolres) S. U. V. 100 F., Seconds 210 F.,Seconds Viscosity Index Viscosity Gravity Constant 210 F Color,Lovibond, 34 Cell a- Carbon Residue, Per Cent Wt r Sulfur, Per Cent Wt-r ar Specific Gr. 60 F. (Pyc 77 F.) S. U. V. 210 F.. Seconds Thesolvent refined oils obtained as described hereinbefore, particularlywhen liquid S02 or liquid SOz-benzol or selecto are used as naphthenicsolvents, can be dewaxed merely by removing a portion of the propane tochill the oil and-adjust the propane concentration to that desirable fordewaxing. In other words, the concentration of propane and organiccarbonate in the rafiinate is adjusted, preferably by vaporization ofthe propane, to provide a ratio of propane to organic carbonate fromabout 3:1 to about 1 :3 by Volume. The vaporization of the propaneserves to chill the raflinate to dewaxing temperatures although theraflinate can be chilled by other suitable means. When adjusting theratio of propane to organic carbonate in the raflinate to provide adewaxing mixture, it is also preferred to adjust the ratio of solventrefined oil to dewaxing mixture in the raflinate to 110.2 to 1:8 with aratio of 1 to 3 preferred.

I claim:

1. In the treatment, of a mixture of paraflinic and non-paraffinichydrocarbons contaminated with asphaltic materials which comprisescontacting' a charge stock containing parafinic hydrocarbons,non-parafiinic hydrocarbons and asphaltic material with twosubstantially mutually immiscible solvents comprising a solvent forparaflinic hydrocarbons and a solvent for nonparaflinic hydrocarbons andseparating a raflinate fraction more paraffinic than said charge stockfrom an extract fraction more non-paraffinic than said charge stock, theimprovement which comprises employing a solvent for non-parafiinichydrocarbons consisting essentially of phenol and cresols and at least1.5 weight per cent added water and a solvent for paraffinichydrocarbons consisting essentially of propane and about 1 to about 20per cent of an organic carbonate.

2. In thetreatment of a mixture of parafiinic and non-paraffinichydrocarbons contaminated with asphaltic material which comprisescontacting a charge stock with propane and a mixture of phenol andcresols in the proportion of 1:1-3. 521-45 by weight, and separating araflinate fraction more parafiinic than said charge stock from anextract fraction more non-paraffinic than said charge stock, theimprovement which comprises employing a mixture of phenol and cresols towhich about 1.5 to about 25 per cent water has been added and propane towhich about 1 to about 20 per cent of an organic carbonate has beenadded.

3. The process as set forth and described in claim 1 wherein the organiccarbonate is diethyl carbonate.

4. The process as set forth and described in claim 2 wherein the organiccarbonate is diethyl carbonate.

5. In the treatment of a mixture of parafiinic and non-parafiinichydrocarbons contaminated with asphaltic material which comprisescontact-- ing a charge stock with propane and cresylic acids in theproportion by weight of 1:1-3.5:1-4.5, and separating a rafiinatefraction more paraifinic than said charge stock from an extract fractionmore non-parafiinic than said charge stock the improvement whichcomprises carrying out the separation in the presence of 1.5 to about 25per cent added water and about 1 to about 20 per cent of an organiccarbonate.

6. The process described and set forth in claim 5 wherein the addedorganic carbonate is diethyl carbonate.

7. The method of treating a mixture of hydro carbons admixed. withasphaltic material and subsequently dewaxing said lmixture of hydrocarbons which comprises contacting a waxy mix ture of paraifinic andnon-parafiinic hydrocar: bons admixed with asphaltic material withliquid,- normally gaseous hydrocarbon, a mixture of phenol and cresolsand an organic carbonate in the ratio of 1 part ofoil to 1-3 parts ofpropane to 1-3 parts of said mixture of phenol and cresols to 0.15 to1.5 parts of organic carbonate all by weight, separating a raffinatephase comprising wax, parafinic hydrocarbons, propane and organiccarbonate from an extract phase comprising non-paraflinic hydrocarbons,asphalt and mixture of phenol and cresols, adjusting the ratio ofpropane to organic carbonate in said rafiinate phase from 1 to 3:0.15 to1.5 by weight to 3:15 to 1:5, chilling said rafilnate to dewaxing temperature and separating high molecular weight paraffinic hydrocarbons fromsaid raffinate phase to provide a solvent treated dewaxed oil.

8. The invention as set forth and described in claim 7 wherein theliquid, normally gaseous hydrocarbon is propane.

9. The invention as set forth and described in claim 7 wherein theorganic carbonate is diethyl carbonate.

10. The invention as set forth and described in claim 7 wherein theliquid, normally gaseous hydrocarbon is propane and the organiccarbonate is diethyl carbonate.

HAROLD C. MYERS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,860,823 Stratford May 31, 19321,912,349 Tuttle May 30, 1933 1,917,910 Sullivan July 11, 1933 2,017,432Bahlke Oct. 15, 1935 2,139,000 Cohen Dec. 6, 1938 2,142,525 Noll Jan.3', 1939 FOREIGN PATENTS Number Country Date 413,307 Great Britain July11, 1934

1. IN THE TREATMENT OF A MIXTURE OF PARAFFINIC AND NON-PARAFFINICHYDROCARBONS CONTAMINATED WITH ASPHALTIC MATERIALS WHICH COMPRISESCONTACTING A CHARGE STOCK CONTAINING PARAFFINIC HYDROCARBONS,NON-PARAFFINIC HYDROCARBONS AND ASPHALTIC MATERIAL WITH TWOSUBSTANTIALLY MUTUALLY IMMISCIBLE SOLVENTS COMPRISING A SOLVENT FORPARAFFINIC HYDROCARBONS AND A SOLBENT FOR NONPARAFFINIC HYDROCARBONS ANDSEPARATING A RAFFI NATE FRACTION MORE PARAFFINIC THAN SAID CHARGE STOCKFROM AN EXTRACT FRACTION MORE NON-PARAFFINIC THAN SAID CHARGE STOCK, THEIMPROVEMENT WHICH COMPRISES EMPLOYING A SOLVENT FOR NON-PARAFFINICHYDROCARBONS CONSISTING ESSENTIALLY OF PHENOL AND CRESOLS AND AT LEAST1.5 WEIGHT PER CENT ADDED WATER AND A SOLVENT FOR PARAFFINICHYDROCARBONS CONSISTING ESSENTIALLY OF PROPANE AND ABOUT 1 TO ABOUT 20PER CENT OF AN ORGANIC CARBONATE.